Fire sprinkler systems are a well-known type of active fire suppression system. Sprinklers are installed in all types of buildings, commercial and residential, and are generally required by fire and building codes for buildings open to the public. Typical sprinkler systems comprise a network of pipes, usually located at ceiling level, that are connected to a reliable water source. Sprinkler heads are disposed along the pipes at regular intervals. Each sprinkler head includes a fusible element, such as a frangible glass bulb, that is heat-sensitive and designed to fail at a predetermined temperature. Failure of the fusible element or glass bulb opens an orifice, allowing water to flow through the head, where it is directed by a deflector into a predetermined spray pattern. Sprinkler systems may suppress a fire, or inhibit its growth, thereby saving lives and limiting inventory loss and structural damage. Sprinkler specifications are published by the National Fire Protection Association (e.g., NFPA 13).
The fire protection sprinkler system is fed from a pump room or riser room. In a large building the fire protection sprinkler system consist of several “zones,” each being fed from a separate riser in the pump room (i.e. a “zone” refers to the piping network tied to one particular riser). The riser contains the main isolation valve and other monitoring equipment (e.g., flow switches, alarm sensors, and the like). The riser is typically a 2, 3, 4, 6, or 8 inch diameter pipe coupled to the building's main water supply. In some cases, the water supply pressure may be increased with a booster pump (called the fire pump). The riser then progressively branches off into smaller branch lines. At the furthest point from the riser, typically at the end of each zone, there is an “inspector's test port,” which is used for flow testing.
The most basic fire protection sprinkler system is a “wet pipe” system, wherein the sprinkler pipes are full of water under a predetermined “internal set point” pressure. If the water pressure decreases below the set point, valves are opened and the pump (if applicable) is activated, and water flows into the sprinkler pipes in an attempt to maintain the pressure. The set point pressure drops when water escapes the system, such as due to the opening of a sprinkler head in the event of a fire.
The pipes are periodically drained, and the piping network is inspected. Parts may be replaced, e.g., where signs of corrosion are observed, to install new functionality, or simply as part of a periodic replacement program. When the system is again filled with water, vents must be opened to allow air or other gas displaced by the water to exit (per 2016 NFPA 13 guidelines). These air vents are installed at high points in the piping network, and include a mechanism, such as a poppet or ball valve, which ideally allows air to escape but blocks the flow of water out of the vent. In practice, some small amount of is water inevitably discharged from the air vent before the water blocking mechanism can fully shut off the water flow. This spillage is at best a nuisance, and may present a hazard if the water were to fall onto, e.g., shopping center floors, computers, other electronic equipment, inventory, etc.
The Background section of this document is provided to place embodiments of the present invention in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Approaches descried in the Background section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.